Gas seal structure

Abstract

A resin sub-seal member ( 11 ) provided with a concave groove ( 16 ) is disposed at a region closer to a higher-pressure side region than a rubber main seal member ( 10 ) and pressure variation in a gas on a higher-pressure side is inhibited from being transmitted to the main seal member ( 10 ). Further, a variation reducing space ( 13 ) is formed between the seal members ( 10 ) and ( 11 ) to be able to reduce the pressure variation when gas leakage in the sub-seal member ( 11 ) occurs or the sub-seal member ( 11 ) responds with a delay with respect to the pressure variation. Thus, rapid change in the pressure of the gas surrounding the main seal member ( 10 ) is inhibited, occurrence of the blistering phenomenon is inhibited, and a high seal ability is achieved. The seal structure is formed by a simple structure including the seal members ( 10 ) and ( 11 ), and the variation reducing space ( 13 ).

The invention claimed is: 
     
       1. A gas seal structure for use with a gas having a high permeability with respect to a rubber material, the gas seal structure comprising:
 a main seal means that is made of the rubber material and is disposed between two seal surfaces; 
 a sub-seal means that is made of resin and is disposed between the two seal surfaces, the sub-seal means being located closer to a higher-pressure region than the main seal means and being provided with a concave groove, the higher-pressure region arranged to receive the gas having a high permeability with respect to a rubber member, such that the sub-seal means is positioned to be exposed to the gas; and 
 a pressure variation reducing means comprising a variation reducing space connected only to a gap located between the main seal means and the sub-seal means, the pressure variation reducing means and the gap located between and defined by the two seal surfaces, the variation reducing space being closed by the main seal means and the sub-seal means such that the variation reducing space is disconnected from atmosphere; and 
 the variation reducing space being formed by a concave portion formed in one of the two seal surfaces, the variation reducing space and the gap each having a volume, and wherein the volume of the variation reducing space is larger than the volume of the gap formed between the two seal surfaces. 
 
     
     
       2. The gas seal structure according to  claim 1 , wherein the sub-seal means is disposed such that the concave groove opens toward the higher-pressure side region. 
     
     
       3. The gas seal structure according to  claim 1 , wherein the sub-seal means is disposed such that the concave groove opens toward a lower-pressure side region. 
     
     
       4. A gas seal structure comprising:
 a main seal comprising a rubber material, the main seal disposed between two seal surfaces, the rubber material having a high permeability when exposed to a gas having a low molecular weight; 
 a sub-seal comprising a resin material, the sub-seal disposed between the two seal surfaces, the sub-seal disposed closer to a higher-pressure region than the main seal; 
 a concave groove formed in the sub-seal; 
 a gap formed between the two seal surfaces adjacent the sub-seal; 
 an enclosed pressure variation reducing space disposed between the main seal and the sub-seal and in flow communication with and bounded on at least one side by the gap, the pressure variation reducing space formed at least in part by a concave portion formed in either of the two seal surfaces and between the main seal and the sub-seal, the concave portion forming a volume greater than a volume of the gap and arranged to inhibit occurrence of a blistering phenomenon in the main seal. 
 
     
     
       5. The gas seal structure according to  claim 4 , wherein the sub-seal is disposed such that the concave groove opens toward the higher-pressure region. 
     
     
       6. The gas seal structure according to  claim 4 , wherein the sub-seal is disposed such that the concave groove opens toward a lower-pressure region, the main seal disposed closer to the lower pressure region than to the sub-seal. 
     
     
       7. A gas seal structure for use with a gas having a high permeability with respect to a rubber material, the gas seal structure comprising:
 first and second opposing seal surfaces, the first and second opposing seal surfaces movable with respect to one another; 
 a concave portion carried by at least the first opposing seal surface; 
 a gap formed between the opposing seal surfaces and formed in part by a first distance between the opposing seal surfaces; 
 a main seal made of the rubber material and disposed between the opposing seal surfaces, the main seal disposed adjacent a lower pressure region; 
 a sub-seal made of resin and disposed between the opposing seal surfaces, the sub-seal disposed adjacent a higher pressure region; 
 the sub-seal having a concave groove oriented toward the higher-pressure region arranged and positioned to be exposed to the gas; and 
 a pressure variation reducing space located between the opposing seal surfaces, the pressure variation reducing space defined by the second opposing seal surface and by the concave portion of the first opposing seal surface, the pressure variation reducing space formed in part by a second distance between the opposing seal surfaces, the second distance greater than the first distance; 
 the pressure variation reducing space disposed between the main seal and the sub-seal but separated from the sub-seal by the gap; and 
 wherein a volume of the pressure variation reducing space is larger than a volume of the gap. 
 
     
     
       8. The gas seal structure according to  claim 7 , wherein the sub-seal is disposed in a sub-seal holding space, and wherein the sub-seal holding space and the variation reducing space are separated by the gap.